“We're family, so there is nothing to be embarrassed about.” Hikaru Miyanishi watches her father-in-law suspiciously when he claims he only came to wash her back. Quiet, intellectual, and usually occupied with his computer, he has never behaved so outrageously before. Before she can find a gentle way to refuse, he corners her against the edge of the tub. When he approaches with a kind expression and soft voice and pulls her into his arms, Hikaru realizes her happy newlywed life has ended. The forbidden encounters occurring in their shared home whenever her husband is away begin twisting the entire family relationship.